Accuracy of implant placement using CAD-CAM tooth-supported surgical guides for an auricular prosthesis in vitro.

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To evaluate the accuracy of tooth-supported surgical guides used to place implants in auricular prostheses. The accuracy (trueness and precision) of the implant positions was evaluated, and the difference between the surgical guide with and without retention of the external auditory canal (EAC) was compared. This study simulated implant placement in vitro for the treatment of right auricle malformation. Surgical guides and other casts were fabricated using additive manufacturing technology. The casts were divided into 2 groups according to the surgical guide, with 10 bone blocks in each group (with or without the EAC plug (Guides 1 and 2)). Three implant positions (Implants 1-3) were prepared for each bone block using surgical guides. Implant positions were registered using light-body silicone impressions combined with optical surface scans to measure the coronal, apical, depth, and angular deviations. Four deviations of trueness and precision were reported as the mean±standard deviation, which was analyzed by Student's t-test. Each group of 10 bone blocks with 30 implant positions was successfully prepared and digitally reproduced as implants. The accuracies of implant position with surgical guides were acceptable when compared with the preoperatively planned implant positions. Compared with the Guide 2 group, there was a significant difference in the apical, depth, and angular deviations of Guide 1 group in terms of precision (p=0.001). There was a significant difference in the depth deviation of Implant 1 (p=0.028) and apical deviation of Implant 2 (p<0.001) compared two groups in terms of trueness. In terms of precision, there was a significant difference in the coronal (p=0.002), apical (p=0.001), and depth (p<0.001) deviation of Implant 1; apical (p=0.036) and angular (p<0.001) deviation of Implant 2 also existed significant difference; the coronal deviation of Implant 3 (p=0.018) also existed significant difference. Moreover, the group with the EAC plug showed lower deviation in precision and a smaller volume in the 95% confidence ellipsoid. Both types of tooth-supported surgical guides can provide acceptable accuracy. A surgical guide with an EAC plug was considered to be more precise.